An English journalist has speculated that Spain's richest woman, the Duchess of Alba, could become queen of a newly independent Scotland should it vote to break from the UK in a referendum scheduled for September.

The unmistakeable 87-year-old Duchess of Alba is one of Spain's best-known figures.

As head of the aristocratic House of Alba she is worth an estimated €3.5 billion ($4.8 billion), according to Spain's Vanity Fair magazine.

Her features are regularly seen in Spanish celebrity magazines, but could they soon be stamped onto Scottish coins and banknotes?

That intriguing possibility was flagged by Peter Osborne, chief political commentator of British newspaper The Telegraph.

The Guinness Book of record ranks her as the most titled aristocrat in the world, but it is just one word of her mighty moniker that gives the clue to a possible Caledonian connection.

Stuart is the name of the dynasty which once ruled all of what is now Great Britain.

They lost their crown when Queen Anne died childless in 1714 but the line continued in other countries.

Osborne speculated that the current Queen of Great Britain, Elizabeth Windsor, might be forced obliged to give up the crown of Scotland in the event of a "Yes" vote in the forthcoming independence elections.

He wrote: "She is constitutionally obliged to take the advice of the [British] Prime Minister, David Cameron.

"Cameron has already denied Scotland the pound sterling. He is entitled to deny the Scots the House of Windsor, especially since the Scots had their own separate monarch before James the VI and I unified the crowns of England and Scotland in 1603."

Osbourne went on to speculate that they might turn to descendants of the House of Stuart instead, of which the Duchess of Alba is one of two leading candidates.

The other is 81-year-old Franz, Duke of Bavaria, whom some believe has a claim to the throne of the whole United Kingdom.

Neither Franz nor the Duchess have formally commented on their possible royal ambitions but she is known to be a staunch monarchist.

She told Spanish news agency Efe in 2013 that "the monarchy is fundamental to the continuity of Spain as a nation" and that Spain's current monarch Juan Carlos was a "great King".

The Duchess is also perhaps too busy to pursue her Stuart heritage. She recently married a man 24 years her junior and is reportedly an active participant in a campaign to ban so-called 'Mega Skyscrapers' in the luxury resort town of Marbella, where she owns property.